Pressure exchangers



Nov. 24, 1964 J. A. C. KENTFIELD PRESSURE EXCHANGERS Filed Oct. 16, 19612 Sheets-Sheet l I M 5 2o 23' 1 I J l 1b H9 '24 7e Hal.

1964 J. A. c. KENTFIELD 3,

PRESSURE EXCHANGERS Filed Oct. 16, 1961 2 Sheets-Sheet 2 United StatesPatent Office 3,158,067 Patented Nov. 24, 1964 3,158,007 PRESSUREEXCHANGERS John Alan Charles Kentfieid, Worthing, England, assignor toPower Jets (Research 8: Deveioprnent) Limited, London, England, aBritish company Filed Oct. 16, 1961, Ser. No. 145,383 Claims priority,application Great Britain Oct. 14, 1960 12 Claims. (Cl. 62401) Thisinvention relates to pressure exchangers.

The term pressure exchanger is used herein to mean apparatus comprisingcells in which one fluid quantity expands, so compressing another fluidquantity with which it is in contact, ducting to lead fluidsubstantially steadily to and from the cells at different pressures andmeans to effect relative motion between the cells and the ducting.

The cells of a pressure exchanger are usually arranged in a circulararray as a rotor and the rotor is customarily termed a cell ring. Apressure exchanger may have a low-pressure scavenging stage and arelatively higher-pressure scavenging stage,'each stage having inlet andoutlet ports in end-plates at opposite ends of the cell ring.

In one proposed form of pressure exchanger, two streams of fluid, one ata high pressure and one at a lower pressure, are introduced into thecells and these streams are combined into a single stream of'fluid at anintermediate pressure issuing from an outlet of the'pressure exchanger.Such a pressure exchanger is hereinafter referred to as a pressureequalizer.

Alternatively, in another proposed form of a pressure exchanger a singlestream of fluid at an intermediate pres sure is introduced into thecells and this stream is divided into two streams of fluid, one at apressure higher and one at a pressure lower than the intermediatepressure, issuing from outlets of the pressure exchanger. Such apressure exchanger is hereinafter referred to as a pressure divider.

To provide a flow of cold fluid which may be used for cooling purposesin an aircraft, it has been suggested previously that both a pressuredivider and a pressure equalizer should be used in combination.According to this prior suggestion, the high-pressure outlet flow andthe lower-pressure outlet flow of the pressure divider provide,respectively, the high-pressure inlet flow and the lowerpressure inletflow of the pressure equalizer. Some of the fluid admitted to thepressure divider at a pressure intermediate the high and lower pressuresis compressed in the cells of the pressure divider with the object onlyof expanding, and so cooling, the remainder of the intermediate-pressureinlet fluid. The high-pressure fluid so produced is then expanded in thepressure equalizer with the object only of compressing thelower-pressure fluid. Thus, some of the intermediate-pressure inletfluid is subject to a compression process followed by an expansionprocess, whilst the remainder of the intermediate-pressure inlet fluidis subject to an expansion process followed by a compression process. vAccording to the present invention, a pressure exchanger incorporates aring of open-ended cells, end-plates effective to close the ends of thecells but'having ports therein for the admission of fluid to and theextraction of fluid from the cells, means to eflect relative movementbetween the cells and the end-plates, an inlet port and an outlet portof the said ports serving as a low-pressure scavenging stage and afurther inlet port and a further outlet port of the said ports servingas a higher-pressure scavenging stage, ducting interconnecting thelow-pressure scavenging stage outlet and inlet ports, the opening edgeof the low pressure scavenging stage inlet port being in advance,considered in the direction of relative movement, of the opening edge ofthe low-pressure scavenging stage outlet port and the low-pressurescavenging stage inlet port providing for a higher volumetric flow offluid than the low-pressure scavenging stage outlet port.

The pressure exchanger as set out in the immediatelypreceding paragraphmay be conveniently referred to as a depressurizer.

By the use of such a depressurizer, the compression process andconsequent expansion process is eliminated, whilst the whole of theexpansion and compression processes take place in the depressurizer andthus the fluid admitted to the cells through the inlet port of thehigher-pressure scavenging stage is expanded in the cells at that stageto produce a supply of low-temperature, low-pressure fluid and issubsequently compressed in the cells before being exhausted from thecells through the outlet port of that stage.

The closing edge of the low-pressure scavenging stage outlet port of thedepres surizer may be in advance of the closing edge of the low-pressurescavenging stage inlet port.

The outlet port of the higher-pressure scavenging stage may lead to theinlet of a diifuser, the outlet of which leads to the inlet of a fan.

If the depressurizer is incorporated in the cooling system of anaircraft, during flight, ram air is supplied to the inlet port of thehigher-pressure scavenging stage and the outlet port of that stage maylead to a duct exhausting to the rear of the aircraft.

if the low-pressure scavenging stage of the depressurizer is used toprovide a flow of coolant fluid for the cold pass of a heat-exchanger,the cold pass may constitute a portion of the ducting interconnectingthe inlet and outlet ports of that stage. Alternatively, if thedepressurizer is used to provide a flow of low-pressure fluid in adrying plant, a drying chamber of the plant may constituted a portion ofthe said interconnecting ducting.

In order to enable-the depressurizer to operate at a higher pressureratio, the outlet port of the higher-pressure scavenging stage may leadto the lower-pressure fluid inlet port of a pressure equalizer, thehigh-pressure inlet port of which is connected to a source ofhigh-pressure fluid. This arrangement improves the scavenging of thecells of the depressurizer at the higher-pressure scavenging stage. Theintermediate-pressure fluid outlet port of the pressure equalizer maylead to the inlet of a diffuser, the outlet of which may be open toatmosphere.

In order to further increase the pressure ratio of the depressurizer,the higher-pressure scavenging stage inlet port of the depressurizer maybe supplied with fluid from the outlet of an expansion engine, the inletof which expansion engine is open to atmosphere. The expansion enginemay be coupled to drive the cell rings of the depressurizer and of thepressure equalizer. An electric motor-generator may also be coupled tothe cell rings and the electric motor-generator controlled in accordancewith the speed of the cell rings.

The following description relates to the accompanying diagrammaticdrawings.

In the drawing, which are given by way of example:

FIGURE 1 is a developed view of a depressurizer for providing a flow ofcooling air for a cooling system;

FIGURE 2 shows the circuit of a drying plant incorporati ng adepressurizer;

FIGURE '3 shows a modified form of the circuit shown in FIGURE 2;

FIGURE 4 shows a modified form of the circuit shown in FIGURES; and

FIGURE 5 shows a vapour compression refrigeration circuit incorporatinga depressurizer.

In FIGURE 1, a depressurizer cell ring 1 is rotatable in a directionindicated by an arrow 2 between end-plates 3 and 4. The end-plate 3 hasa low-pressure fluid outlet port and a higher-pressure fluid inlet port6. The endplate 4 has a low-pressure fluid inlet port 7 and anintermediate-pressure fluid outlet port 8. The ports 5 and 7 serve as alow-pressure scavenging stage. The ports 6 and 8 serve as a relativelyhigher-pressure scavenging stage. The port 5 leads via a duct 9 to aport 7. A heatexchanger has a cold pass 10 formed by part of the duct 9.A hot-pass 11 of the heat-exchanger carries the flow of fluid to becooled.

The port 6 is open to atmosphere, whilst the port 8 leads to the inletof a diffuser 12, the outlet of which leads to the inlet of a fan 13coupled to an electric motor 14 by a shaft 15. The outlet of the fan 13is open to atmosphere. An electric motor 16 is arranged to drive thecell ring 1 through a shaft 17. Compression waves are represented bysingle full lines 18, 19, and 21, expansion waves by a fan of brokenlines 22 and an ideal interface line between the fluids in the cells isrepresented by a chain line 23.

In operation, the cell ring 1 is rotated in the direction of the arrow 2by the electric motor 16 and the fan 13 is driven by the electric motor14. Immediately on starting, cells approaching the port 8 of thehigher-pressure scavenging stage contain air at substantiallyatmospheric pressure and owing to the operation of the fan 13, asub-atmospheric pressure obtains at the port 8. Owing to this pressurediiference, when each cell opens to the port 8, the fan of expansionwaves 22 is set up and travels across the cell accelerating the contentsof the cell out of the port 8. When the rotor has reached itsoperational speed, the waves 22 arrive at the endaplate 3 as each cellis closing to the port 6. The waves 22 are then reflected from theend-plate 3 and traverse the cell reaching the end-plate 4 as the cellis closing to the port 8. Cells leaving the higher-pressure scavengingstage and approaching the low-pressure scavenging stage thereforecontain air at sub-atmospheric pressure. Each of these cells is thenopened to the port 7 where air at a pressure higher than that in thecell exists and the compression wave 18 traverses the cell followed byair from the port 7. The wave 18 reaches the end-plate 3 as each cell isopening to the port 5.

At this stage the relevant cell now contains air at a pressure slightlylower than the pressure at the port 5 and this pressure differencecauses the compression wave 19 to traverse the cell against the flow ofair therein. In so doing, the compression wave 19 converts some of thevelocity of that air into pressure. The conversion of velocity intopressure gives a sufficient increase in pressure to enable the air topass out of the cells. The air which has approached the low-pressurescavenging stage in the cells, passes out of the cells through the port5 and so via the duct 9 through the cold pass 10 of the heat-exchanger,where it is heated by the fluid passing through the hot pass 11, andre-enters the cells via the port 7. Closure of each cell to the port 5causes the compression wave 2% to traverse the cell, thus bringing thecontents of the cell to a pressure just below atmospheric. Thecompression waves 19 and 20 reach the end-plate 4 as each cell isclosing to the port 7.

The absence of incident expansion waves at the lowpressure scavengingstage, permits a more accurate selection to be made of the optimumpositions of the opening edge, that is the radially extending edge ofthe port first encountered by a given cell and closing edge, that is theradially extending edge of the port last encountered by a given cell, ofthe ports. This follows from the fact that an expansion wave is not, infact, a single wave, but a divergent fan of waves.

The compression wave 19 causes a sufficient pressure rise at thelow-pressure scavenging stage to overcome the losses in the port 5, theduct 9, the port 7 and the cells located at the low-pressure scavengingstage.

The port 7 permits a higher volumetric flow of fluid to enter the cellsthan the volumetric flow of fluid which is allowed to leave the cellsvia the port 5. In the embodiment of the invention herein described, thehigher volumetric flow is achieved by arranging that the opening edge 7Aof the port 7 is in advance of the opening edge 5A of the port 5, andthat the closing edge 58 of the port 5 is in advance of the closing edge78 of the port 7.

Air which has entered the cells via the port 7 is conveyed from thelow-pressure scavenging stage in the cells and is at a pressure lowerthan atmospheric pressure. As each cell is opened to the port 6, thecompression wave 21 traverses the cell followed by air at the port 6.The compression wave 21 reaches the end-plate 4 as the cell is againopening to the port 8 and the cycle is recommenced.

If the cooling system of FIGURE 1 is used in an aircraft, during flight,ram air is supplied to the port 6 and the fan 13 is omitted. The flowthrough the port 8 is exhausted to the rear of the aircraft.

In the cooling system of FIGURE 1, the stream of fluid passing throughthe hot pass 11 of the heat-exchanger is indirectly cooled by the streamof air passing through the cold pass 10 of the low-pressure scavengingstage circuit 5, 9 and 7. However, the circuits of drying plants shownin FIGURES 2, 3 and 4, now to be described, a material to be dried isinserted in the low-pressure scavenging stage circuit of thedepressurizer.

Referring to FIGURE 2, a depressurizer 24, having a cell ring (notshown), has inlet and outlet ports, diffuser, fan, electric motors andshafts similar to those described in the embodiment of FIGURE 1. Theoutlet port 5 leads via a duct 25 to the inlet port 7. The duct 25 thusreplaces the integers 9 and 10 of FIGURE 1 and with the ports 5 and 7forms the low-pressure scavenging stage. An auxiliary inlet duct 26leading into the duct 25 has a throttle valve 27.

In operation, the material to be dried is inserted in the duct 25, theelectric motor 16 drives the cell ring of the depressurizer 24, whichfunctions as described with reference to FIGURE 1 and the fan 13 isdriven by the motor 14. The auxiliary inlet duct 26 conveys fluid (forexample atmospheric air) into the duct 25 of the lowpressure scavengingstage and the quantity of the fluid is controlled by the throttle valve27 so as to maintain the flow of fluid in the port 7 at a valueconsistent with satisfactory operation of the drying process.

In the circuit shown in FIGURE 3, a pressure equalizer 28 is alsocoupled to be driven by the electric motor 16. The pressure equalizer 28has a high-pressure fluid inlet port 29 in communication with a sourceof high pressure fluid, a lower-pressure fluid inlet port 30 and anintermediate-pressure fluid outlet port 31. The outlet port 8 of thedepressurizer 24 leads to the lower-pressure fluid inlet port 30 of thepressure equalizer 28.

In operation, corresponding parts of this circuit func tion in the samemanner as described with reference to FIGURE 2. The pressure equalizer28, however, is supplied with a high-pressure fluid through the inletport 29 and the inlet port 30 is supplied with fluid from the outletport 8 of the depressurizer 24. Fluid at a pressure intermediate thehigh and lower pressures of the fluid supplied to the pressure equalizeris discharged from the pressure equalizer via the outlet port 31 and thedifiuser 12.

The addition of the pressure equalizer 28 to the circuit as shown inFIGURE 2 enables the depressurizer 24 to operate at a higher pressureratio by improving scavenging of the cells via the port 8. This improvedscavenging results in the cells that are leaving the higher-pressurescavenging stage containing fluid at a lower pressure than is the casein the arrangement shown in FIGURE 1 and consequently, the low-pressurescavenging stage operates at a lower fluid pressure.

To obtain an even lower fluid pressure in the lowpressure scavengingstage, the fluid entering the port 6 of the depressurizer 24 may firstbe passed through an expansion engine. A circuit including such anexpansion engine in the form of a turbine 32 is shown in FIGURE 4. Inthis figure, the turbine 32 is coupled to the cell rings of thedepressurizer and the pressure equalizer by the shafts 1'7 and theelectric motor 16 shown in FIG- URES 2 and 3 is replaced by an electricmotor-generator 33. This replacement allows power to be taken from theshafts 17 when the amount of Work available at the turbine 32 exceedsthat which is required to drive the cell rings. With this arrangement,it is advantageous to control the motor-generator 33 in accordance withthe speed of the shafts 17 and thus provide shaft speed-governing means.In other respects, a system having a circuit as shown in FIGURE 4functions as described with reference to FIGURE 3.

In FIGURE 5, the depressurizer 24 and a rotary compressor 34 are coupledto be driven by an electric motor 35 via shafts 36. The ports 5 and 7 ofthe depressurizer 24 are interconnected by a duct 37 including anevaporator having a cold pass 38. The port 8 leads via a duct 39 to theinlet of the compressor 34, the outlet of which leads, via a duct 40including a hot pass 41 of a condenser, to the port 6. The circuit isfilled with a suitable quantity of a refrigerant such as ammonia.

In operation, the rotor of the compressor and the cell ring of thedepressurizer are driven by the electric motor 35. The refrigerant iscompressed in the compressor 34 and passes, via the duct 40, through thehot pass 41 Where it is cooled and condensed to a wet vapour. Therefrigerant then enters the cell ring of the depressurizer 24 via theport 6 where it is further cooled in passing through the fan ofexpansion waves 22, FIGURE 1. The refrigerant leaves the cell ring viathe port 5 and passes through the duct 37, a part of which constitutesthe cold pass 38, where it is heated and vaporised, to re-enter the cellring via the port 7 and leave the cell ring via the port 8. The cycle isthen recommenced.

A vapour compression refrigeration plant incorporating a depressurizeras described, offers the advantage of increased capacity over theconventional compressor-restrictor vapour compression plants.Furthermore, the cell ring of the depressurizer will sufler less erosiondamage due to impingement of the refrigerant liquid on the inter-cellwalls than would turbine blades if a turbine were used as an expander inplace of the depressurizer.

I claim:

1. A pressure exchanger incorporating a ring of openended cells,end-plates effective to close the ends of the cells but having portstherein for the admission of fluid to and the extraction of fluid fromthe cells, means to elfect relative movement between the cells and theendplates, an inlet port and an outlet port of the said ports serving asa low-pressure scavenging stage and a further inlet port and a furtheroutlet port of the said ports serving as a higher-pressure scavengingstage, ducting interconnecting the low-pressure scavenging stage outletand inlet ports, the opening edge of the low-pressure scavenging stageinlet port being in advance, considered in the direction of relativemovement, of. the opening edge of the low-pressure scavenging stageoutlet port and the low-pressure scavenging stage inlet port providingfor a higher volumetric flow of fluid than the low-pressure scavengingstage outlet port.

2. A pressure exchanger as claimed in claim 1, in which the closing edgeof the low-pressure scavenging stage outlet port is in advance,considered in the direction of relative movement, of the closing edge ofthe low-pressure scavenging stage inlet port. I

3. A pressure exchanger as claimed in claim 1 including aheat-exchanger, a hot pass and a cold'pass of the heat exchanger, thecold pass of which constitutes a portion of the interconnecting ducting.

4. A pressure exchanger as claimed in claim 1 including a diffuser and afan, the outlet port of the higherpressure scavenging stage leading tothe inlet of the diffuser, the outlet of which leads to the inlet of thefan.

5. Refrigeration plant, incorporating a pressure exchanger as claimed inclaim 1, including an evaporator which constitutes a portion of theinterconnecting ducting, a compressor, the outlet port of thehigher-pressure scavenging stage leading to the inlet of the compressor,a duct communicating with the outlet of the compressor and a condenserinterposed in said duct, the duct terminating at the inlet port of thehigher-pressure scavenging stage.

6. Aircraft plant, incorporating a pressure exchanger as claimed inclaim 3, including means to compress air by ram effect, ducting betweenthe said means and the inlet port of the higher-pressure scavengingstage, a nozzle facing rearwardly of the aircraft and a ducting throughwhich the fluid flow in the outlet port of the higher-pressurescavenging stage can be exhausted to atmosphere via said nozzle.

7. Plant as claimed in claim 6, including a pressure equalizer having ahigher pressure inlet port, a lower pressure inlet port and anintermediate pressure outlet port, and a source of high pressure fluidthe higher-pressure scavenging stage outlet port of the pressureexchanger being connected to the lower-pressure fluid inlet port of thepressure equalizer, the intermediate-pressure fluid outlet port of thepressure equalizer being connected to the inlet of the rearwardly-facingnozzle, and the highpressure fluid inlet port of the pressure equalizerbeing connected to the source of high-pressure fluid.

8. Plant as claimed in claim 6, including an expansion engine, throughwhich ram air can be supplied from the means to compress air to thehigher-pressure scaveng ing stage inlet port of the pressure exchanger.

9. Plant incorporating a pressure exchanger as claimed in claim 1,including a drying chamber which constitutes a portion of the saidinterconnecting ducting of the lowpressure scavenging stage.

10. Plant as claimed in claim 9, including a source of high pressurefluid and a diffuser the outlet of which is open to atmosphere, thehigher-pressure scavenging stage outlet port of the pressure exchangerleading to the lower-pressure fluid inlet port of a pressure equalizerand the intermediate-pressure fluid outlet port of the pressureequalizer leading to the inlet of the diffuser, the highpressure fluidinlet port of the pressure equalizer'communicating with the source ofhigh-pressure fluid.

11. Plant as claimed in claim 9, including an expansion engine, theoutlet of which communicates with the higher-pressure scavenging stageinlet port of the pressure exchanger, the inlet of the expansion enginebeing open to atmosphere.

12. Plant as claimed in claim 9, including a source of high-pressurefluid, a diffuser the outlet of which is open to atmosphere, a pressureequalizer having a higher pressure inlet port, a lower pressure inletport and an intermediate pressure outlet port, ducting forming acommunication between the-higher-pressure scavenging stage outlet portof the pressure exchanger and the lower-pressure fluid inlet port of thepressure equalizer, ducting forming a communication between the sourceof high-pressure fluid and the higher-pressure fluid inlet port of thepressure equalizer and ducting forming a communication between theintermediate-pressure fluid outlet port of the pressure equalizer andthe inlet of the diffuser.

References Cited in the file of this patent UNITED STATES PATENTS2,848,871 Jendrassik Aug. 26, 1958 2,952,982 Spalding Sept. 20, 1960FOREIGN PATENTS 159,112 Australia Sept. 29, 1954

1. A PRESSURE EXCHANGER INCORPORATING A RING OF OPENENDED CELLS,END-PLATES EFFECTIVE TO CLOSE THE ENDS OF THE CELLS BUT HAVING PORTSTHEREIN FOR THE ADMISSION OF FLUID TO AND THE EXTRACTION OF FLUID FROMTHE CELLS, MEANS TO EFFECT RELATIVE MOVEMENT BETWEEN THE CELLS AND THEENDPLATES, AN INLET PORT AND AN OUTLET PORT OF THE SAID PORTS SERVING ASA LOW-PRESSURE SCAVENGING STAGE AND A FURTHER INLET PORT AND A FURTHEROUTLET PORT OF THE SAID PORTS SERVING AS A HIGHER-PRESSURE SCAVENGINGSTAGE, DUCTING INTERCONNECTING THE LOW-PRESSURE SCAVENGING STAGE OUTLETAND INLET PORTS, THE OPENING EDGE OF THE LOW-PRESSURE SCAVENGING STAGEINLET PORT BEING IN ADVANCE, CONSIDERED IN THE DIRECTION OF RELATIVEMOVEMENT, OF THE OPENING EDGE OF THE LOW-PRESSURE SCAVENGING STAGEOUTLET PORT AND THE LOW-PRESSURE SCAVENGING STAGE INLET PORT PROVIDINGFOR A HIGHER VOLUMETRIC FLOW OF FLUID THAN THE LOW-PRESSURE SCAVENGINGSTAGE OUTLET PORT.